Messages in this thread | | | From | Tom Zanussi <> | Subject | [PATCH v2 0/4] tracing: synth_event_trace fixes | Date | Fri, 14 Feb 2020 16:56:37 -0600 |
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Hi Steve,
This is v2 of this patchset. It adds a new patch, 'tracing: Fix number printing bug in print_synth_event()' that fixes the problem you reported with (null) printing in the synth event trace output on 32-bit systems. It turns out to be nothing to do with these fixes or the new stuff in 5.6 - the problem exists in 5.5 as well and can also cause oopses as well when reading the trace file when synthetic evens are present.
The only other change from v1 is a change to 'tracing: Check that number of vals matches number of synth event fields' to not directly return -EINVAL, but only after calling __synth_event_trace_end().
I've tested on both 32-bit x86 and x86_64, both the synth module test and selftests and everything looks ok here.
Thanks,
Tom
v1 text:
Sorry, it took me some time to get a 32-bit x86 system up and running here in order to build and test things on i386. These patches pass both selftests and the synth_event_gen_test testing, although the bug where (null) prints after every integer field in the trace output is still there and is there even before these or yesterday's patches - I have a suspicion it's been there for awhile but nobody looked at synthetic event trace output on i386. In any case, I'm going to continue looking into that - it's a weird situation where nothing gets put in the final %s in the format string on i386 so shows as (null), even though it looks like it's there. Anyway..
Here are 3 bugfix patches, the first of which fixes the bug seen by the test robot, and the other two are patches that fix a couple things I noticed when doing the first patch.
The previous patch I sent, changing u64 to long for the test robot bug did fix that problem too, but on i386 systems that would reduce every field to 32 bits, which isn't what we want either. The new patch doesn't change the code in synth_event_trace() - it still uses u64 just like synth_event_trace_array() which takes an array of u64. Without any further information such as a format string, I don't know of a better way to deal with the varargs version, other than require it get passed what it expects, u64 params.
The second patch adds the same endianness fix as for trace_event_raw_event_synth(), and the last one just adds back a missing check fot synth_event_trace() and synth_event_trace_array().
Thanks,
Tom
The following changes since commit 359c92c02bfae1a6f1e8e37c298e518fd256642c:
Merge tag 'dax-fixes-5.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm (2020-02-11 16:52:08 -0800)
are available in the git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/zanussi/linux-trace.git ftrace/synth-event-gen-fixes2-v2
Tom Zanussi (4): tracing: Make sure synth_event_trace() example always uses u64 tracing: Make synth_event trace functions endian-correct tracing: Check that number of vals matches number of synth event fields tracing: Fix number printing bug in print_synth_event()
kernel/trace/synth_event_gen_test.c | 34 ++++++------ kernel/trace/trace_events_hist.c | 108 +++++++++++++++++++++++++++++++++--- 2 files changed, 116 insertions(+), 26 deletions(-)
-- 2.14.1
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